• Korean Journal of Food Science and Technology
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• v.36 no.4
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• pp.553-557
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• 2004

Aroma compounds in Pholiota adiposa were extracted by simultaneous distillation and extraction (SDE), and 41 compounds were identified by GC-MS, including eleven alcohols, eight aldehydes, four esters, four ketones, nine alkans, and five miscellaneous compounds. Major aroma compounds included hexanal (8.55%), n-heptaldehyde (13.02%), 2-pentyl furan (4.82%), benzeneacetaldehyde (3.34%), (E,Z)-2,4-decadienal (3.06%), and hexacosane(5.04%). Drying method was applied to aroma compounds of Pholiota adiposa extracted by solid phase microextraction and identified by GC-MS. As hot air-drying temperature increased, peak areas (%) of 2-phenylethanol and benzeneacetaldehyde decreased, whereas those of 2(5H)-furanone (0.16%), 2H-1-benzopyran-2-one (7.63%), 2-acetylpyrrole (5.49%), and 4-phenyl-pyridine (5.61%) increased significantly at $70^{\circ}C$.

• Asian Journal of Atmospheric Environment
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• v.11 no.2
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• pp.96-106
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• 2017

In this study, measurements of size-segregated particulate matter (PM) emitted from the combustion of rice straw, pine needles, and sesame stem were conducted in a laboratory chamber. The collected samples were used to analyze amounts of organic and elemental carbon (OC and EC), water-soluble organic carbon (WSOC), humic-like substances (HULIS), and ionic species. The light absorption properties of size-resolved water extracts were measured using ultraviolet-visible spectroscopy. A solid-phase extraction method was first used to separate the size-resolved HULIS fraction, which was then quantified by a total organic carbon analyzer. The results show that regardless of particle cut sizes, the contributions of size-resolved HULIS ($=1.94{\times}HULIS-C$) to PM size fractions ($PM_{0.32}$, $PM_{0.55}$, $PM_{1.0}$, and $PM_{1.8}$) were similar, accounting for 25.2-27.6, 15.2-22.4 and 28.2-28.7% for rice straw, pine needle, and sesame stem smoke samples, respectively. The $PM_{1.8}$ fraction revealed WSOC/OC and HULIS-C/WSOC ratios of 0.51 and 0.60, 0.44 and 0.40, and 0.50 and 0.60 for the rice straw, pine needle, and sesame stem burning emissions, respectively. Strong absorption with decreasing wavelength was found by the water extracts from size-resolved biomass burning aerosols. The absorption ${\AA}ngstr{\ddot{o}}m $ exponent values of the size-resolved water extracts fitted between 300 and 400 nm wavelengths for particle sizes of $0.32-1.0{\mu}m$ were 6.6-7.7 for the rice straw burning samples, and 7.5-8.0 for the sesame stem burning samples. The average mass absorption efficiencies of size-resolved WSOC and HULIS-C at 365 nm were 1.09 (range: 0.89-1.61) and 1.82 (range: 1.33-2.06) $m^2/g{\cdot}C$ for rice straw smoke aerosols, and 1.13 (range: 0.85-1.52) and 1.83 (range: 1.44-2.05) $m^2/g{\cdot}C$ for sesame stem smoke aerosols, respectively. The light absorption of size-resolved water extracts measured at 365 nm showed strong correlations with WSOC and HULIS-C concentrations ($R^2=0.89-0.93$), indicating significant contribution of HULIS component from biomass burning emissions to the light absorption of ambient aerosols.

• Journal of Food Hygiene and Safety
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• v.31 no.6
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• pp.432-438
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• 2016

Ethoxyquin (EQ, 1,2-dihydro-6-ethoxy-2,2,4-trimethyl-quinoline) is quinoline-based antioxidant used in the animal feed and food industry to protect the raw materials and final products against oxidation. In recent years the use of synthetic antioxidants in fishmeal ingredients carry-over to farmed fish fillets has received increasing attention in food safety. This study was conducted to develop an analytical method to determine EQ in aquatic products. The analytes were confirmed and quantified via liquid chromatography-tandem mass spectrometry (LC-MS/MS) in the positive ion mode using multiple reaction monitoring (MRM). The sample was extracted with 1 N HCl (in case of flatfish extracted with 1 N HCl containing 10% acetonitrile). Then, solid phase extraction (SPE) was used for the cleanup. Standard calibration curves presented linearity with the correlation coefficient ($r^2$) > 0.99, analyzed at 0.005-0.2 mg/kg concentration. The developed method was validated according to the Codex Alimentarius Commission (CAC) guideline. The limits of quantitation for EQ were 0.01 mg/kg. Average recoveries ranged from 81.3% to 107%. The repeatability of measurements, expressed as the coefficient of variation (CV, %), was below 10%. The analytical method was characterized with high accuracy and acceptable sensitivity to meet CODEX guideline requirements and would be applicable to analyze the EQ residue in aquatic products.

• Korean Journal of Food Science and Technology
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• v.46 no.1
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• pp.7-12
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• 2014

A sensitive and simple analytical method to identify flutianil residues in agricultural commodities was developed and validated using gas chromatography-electron capture detection (GC-ECD) and mass spectrometry (GC-MS). The flutianil residues were extracted with acetonitrile, partitioned with dichloromethane, and then purified using a silica solid-phase extraction (SPE) cartridge. The method was validated using pepper, sweet pepper, mandarin, hulled rice, soybean, and potato spiked with 0.02 or 0.2 mg/kg flutianil. The average recovery of flutianil was 76.5-108.0% with a relative standard deviation of less than 10%. The limit of detection and limit of quantification were 0.004 and 0.02 mg/kg, respectively. The result of recoveries and relative standard deviation were in line with Codex Alimentarius Commission Guidelines (CAC/GL 40). These results show that the method developed in this study is appropriate for flutianil identification and can be used to maintain the safety of agricultural products containing flutianil residues.

• Korean Journal of Food Science and Technology
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• v.47 no.5
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• pp.556-560
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• 2015

This study was aimed at investigating the natural occurrence of caffeine, theobromine, and theophylline in tea leaves. Sample clean-up was based on a simple solid phase extraction (SPE) treatment, and simultaneous analysis was performed by high performance liquid chromatography (HPLC). This method showed good results in terms of linearity, recovery, precision, limit of detection (LOD), and limit of quantitation (LOQ). The caffeine, theobromine, and theophylline contents of tea leaves (n = 228) ranged from 5.4 to 58.2 mg/g, from not detected to 11.2 mg/g, and from not detected to 0.7 mg/g, respectively. The results obtained in this study can be used as fundamental data of caffeine, theobromine, and theophylline contents in tea leaves.

• Analytical Science and Technology
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• v.26 no.2
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• pp.142-153
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• 2013

A new, rapid, and simple analytical method was developed and validated using high performance liquid chromatograph-photodiode array detector (HPLC-PAD) for the determination of lepimectin residues in agricultural commodities. The lepimectin residues in samples were extracted with methanol, partitioned with dichloromethane, and then purified with glass column filled with subsequently to aminopropyl ($NH_2$) solid phase extraction (SPE) cartridge. The purified samples were detected using HPLC-PAD. Correlation coefficient ($R^2$) of both lepimectin $A_3$ and $A_4$ solutions were 0.9999. The method was validated using cucumber spiked with lepimectin at 0.02 and 0.2 mg/kg and pepper, mandarin, hulled rice, potato, soybean at 0.02 and 0.5 mg/kg. Average recoveries were 76.0~114.8% with relative standard deviation less than 10%, and limit of detection (LOD) and limit of quantification (LOQ) were 0.005 and 0.01 mg/kg, respectively. The result of recoveries and overall coefficient of variation of a laboratory results in Gwangju regional KFDA and Daejeon regional KFDA was followed with Codex guideline (CAC/GL 40). Therefore, developed method in this study is accurate, rapid, and appropriate for lepimectin determination and will be used to keep safety of lepimectin residues in agricultural products.

• Journal of Korean Society of Environmental Engineers
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• v.28 no.2
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• pp.223-228
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• 2006

High-performance liquid chromatography(HPLC) and fluorescence derivatization were applied for a trace-level N-nitrosodimethylamine(NDMA) analysis of water samples. Fluorescence intensity was optimized with the excitation wavelength of 340 nm and the emission wavelength of 530 nm. pH adjustment after denitrosation was necessary to get a maximum intensity at pH between 9 and 12. Maximum intensity was found with a dansyl chloride concentration of 330 to 500 mg/L. Percentile error in the water sample analyses through solid phase extraction was 12-162% and 6-23% for the lower concentration level(10-200 ng/L NDMA) and the higher level(100-1000 ng/L NDMA), respectively, showing more discrepancy in lower level. However, the average ratios of estimated NDMA to the standard NDMA were close to 1 for both concentration ranges, presenting this HPLC method could detect from tens to hundreds nanograms NDMA per liter. Accurate determination of NDMA, which was injected to a wastewater effluent, revealed the selectivity of fluorescence derivatization for the target compound(NDMA) in the presence of complex interfering compounds. The HPLC with fluorescence derivatization may be applicable for determining NDMA of water and wastewater samples fur various research purposes.

• The Journal of the Korea Contents Association
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• v.9 no.11
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• pp.262-270
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• 2009

$^{18}F$-mefway has been developed as radioligand for serotonin receptor 5-$HT_{1A}$. The object of this study was to obtain the mefway precursor with the higher yield than previous method and to identify whether $^{18}F$-mefway can bind to 5-$HT_{1A}$ or not. from microPET imaging of small animal brain. Precursor was prepared by a modification of the reported procedure then [$^{18}F$] labeling was performed by adding $^{18}F$ ion at $130^{\circ}C$ in the hot cell for 30min. After purification of reaction mixture using alumina Sep-pak and HPLC, microPET images of small animal brain were determined. The chemical yield of precursor was increased from 9% to 34% using oxalyl chloride and LAH/diethylether. We synthesized a precursor which was successfully labeled with no-carrier-added $^{18}F$-by new synthetic route. This research suggest that $^{18}F$-mefway will be used a radiopharmaceutical for evaluation of central nerve system disorder as imaging a gent for 5-$HT_{1A}$ receptor.

• Journal of Environmental Health Sciences
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• v.38 no.1
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• pp.8-17
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• 2012

Objectives: Perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) are man-made, persistent global pollutants widely diffused throughout the environment. They have been even found in the cord blood and breast milk of humans. Furthermore evidence of developmental toxicity in animals exists. To assess the distribution of maternal and fetal exposure to PFOS and PFOA, we analyzed paired maternal blood, cord blood and breast milk samples. Methods: Maternal blood, cord blood and breast milk were collected from 150 volunteers from the general population (aged 20-40, mean $30.5{\pm}2.9$) of the city of Busan in 2009-2010. The samples were extracted using the weak anion exchange and solid-phase extraction methods and quantified by high-performance liquid chromatograph (HPLC, Agilent 1200 Series) coupled with an Triple Quad LC-MS/MS system (Agilent 6410). Results: Median PFOA and PFOS concentrations in maternal blood were 2.18 and 3.32 ng/ml, in cord blood were 0.83 and 0.58 ng/ml, and in breast milk were 0.13 and 0.11 ng/ml, respectively. PFOS and PFOA concentrations were significantly correlated among matrices (Spearson's ${\rho}=0.226$, p = 0.05 for maternal blood; ${\rho}=0.736$, p < 0.01 for cord blood; ${\rho}=0.493$ p < 0.01 for breast milk). The ratio of cord blood/maternal blood was 0.39 for PFOA and 0.19 for PFOS. The ratio of breast milk/maternal blood was 0.07 for PFOA and 0.06 for PFOS. Conclusions: Our findings suggest that PFOA and PFOS exposure through the placenta was more prominent than through breast milk among Korean neonates born in Busan. The transfer efficiency of maternal blood to breast milk was similar between PFOA and PFOS, but that of maternal blood to cord blood was higher in PFOA than PFOS.

• Journal of Environmental Health Sciences
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• v.40 no.2
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• pp.114-126
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• 2014

Objectives: We aimed to develop a measurement method of five metabolites of trichloroethylene (TCE) in a concurrent biological sample, e.g., trichloroacetic acid (TCA), dichloroacetic acid (DCA), S-(1,2-dichlorovinyl) glutathione (DCVG), S-(1,2-dichlorovinyl)-L-cysteine (DCVC), and N-Acetyl-S-(1,2-dichlorovinyl)-L-cysteine (NAcDCVC) and to validate the method before application to pharmacokinetic study. Methods: TCE metabolites were simultaneously analyzed using high performance liquid chromatography coupled with electrospray ionization mass spectrometry (HPLC-ESI-MS/MS) with as little as 50 ${\mu}L$ of serum and urine. DCA, TCA and NAcDCVC were extracted with diethyl ether, while DCVC and DCVG were extracted by solid phase extraction. This method was validated according to the guidelines for bioanalytical method validation of the Korean National Institute of Toxicological Research. Then, we determined the five metabolites in five strains of mice at 24 hr after exposure to 1 g TCE /kg body weight. Results: The limits of detection for the five metabolites in biological samples ranged from 0.001 to 0.076 nmol/mL, which is comparable to or better than those previously reported. Most calibration curves showed good linearity ($R^2=0.99$), and between-batch variation was less than 20% expressing acceptable robustness and reproducibility. Using this method, we found TCA and DCA were detected in all test mice at 24 hr after the oral administration while NAcDCVC and DCVC were detected in some strains, which showed strain-dependent metabolism of TCE. Conclusions: The present method could provide robust and accurate measurements of major key metabolites of TCE in biological media, which allowed concurrent analysis of TCE metabolism for limited amounts of biospecimens.